The invention relates to a semiconductor facility, and in particular to a wafer probe.
FIG. 1a is a schematic view of a test head 100 of a conventional wafer probe. As shown in FIG. 1a, the test head 100 comprises a body 130, a first restricting element 121, a second restricting element 122, a printed circuit board (PCB) 110, a clamping element 140, and a probe head 170. The first restricting element 121 and the second restricting element 122 clamp the PCB 110 to restrict deformation of the PCB 110. A connecting portion 131 and the PCB 110 are fixed together via a positioning portion 124 such as a zero insertion force socket (ZIF). The test head body 130 connects to the PCB 110 by the connecting portion 131. The clamping portion 140 clamps the PCB 110. The probe head 170 is connected to the PCB 110 with probe pins 171 thereon. A wafer carrier 160 is disposed under the test head 100.
FIG. 1b is a schematic view when the test head 100 is testing a wafer 150. When the wafer 150 is disposed on the wafer carrier 160, during probing, the test head 100 moves down and an end of each probe pin 171 is inserted into the wafer 150 such that the test head 100 begins examining the wafer 150.
FIG. 2a is a schematic view of the PCB 110 and the probe head 170 when the wafer probe is idle. At this time, the PCB 110 and the probe head 170 are not deformed. Please also refer to FIGS. 1b and 2b, when the wafer probe begins, the wafer carrier 160 produces heat on the PCB 110 and the probe head 170 such that the PCB 110 and the probe head 170 is pre-heated. During the pre-heating procedure, heat is transferred from the wafer carrier 160 to the PCB 110 and the probe head 170 such that upper surfaces of the PCB 110 and the probe head 170 have higher temperature than the lower surfaces. The PCB 110 and the probe head 170 deform downward due to thermal expansion and contraction. As shown in FIG. 2c, after a period of pre-heat time, since heat is accumulated to a certain level, the PCB 110 and the probe head 170 are turned out to curve upward to reach a stable state. In the deformation process mentioned above, the deformation of the PCB 110 and the probe head 170 is leading by the deformation of the PCB 110, because the volume of the PCB 110 is greater than that of the probe head 170.
Additionally, as shown in FIG. 3a, the wafer 150 has a plurality of probe marks 151 for insertion of probe pins 171 and testing the wafer 150. FIGS. 3b, 3c and 3d show relations between the probe pins 171 and the probe marks 151. With reference to FIG. 3b, when the pre-heat procedure is not applied, some probe pins 171 dislocate from the probe marks 151 for compensating the following deformation. Then, with reference to FIG. 3c, when preheat procedure is applied, the probe head 170 deforms downward, and some probe pins 171 dislocate from the probe marks 151. Finally, when the probe head 170 curves upward, ends of the probe pins 171 are aiming at the probe marks 151.
The PCB 110 and the probe head 170, however, achieve the stable state in FIGS. 2c and 3d after a period of time. Thus, the testing time is longer.